SiOx-based resistive switching memory integrated in nanopillar structure fabricated by nanosphere lithography

textA highly compact, one diode-one resistor (1D-1R) SiOx-based resistive switching memory device with nano-pillar architecture has been achieved for the first time using nano-sphere lithography. The average nano-pillar height and diameter are 1.3 μm and 130 nm, respectively. Low-voltage electroforming using DC bias and AC pulse response in the 50ns regime demonstrate good potential for high-speed, low-energy nonvolatile memory. Nano-sphere deposition, oxygen-plasma isolation, and nano-pillar formation by deep-Si-etching are studied and optimized for the 1D-1R configurations. Excellent electrical performance, data retention and the potential for wafer-scale integration are promising for future non-volatile memory applications.Materials Science and Engineerin

Haigui's predicament in the job market : is there opportunity at the end of the tunnel?

textDriven by the desire for a bright future and a successful career, many young people in China are embarking on overseas odysseys to pursue higher education degrees in order to get decent jobs when they return to China. Those people who are educated abroad and come back with higher education diplomas are called "Haigui" in Chinese. Although they excel in their fields and are capable of the occupations that they dream of, most of them fail to get the jobs they so crave because of reasons beyond their control, such as the slump of the job market, unfair parental privilege, and the high density of Haigui in large cities. This story depicts the job-hunting experiences of four characters -- Ye, Zhang, Erin and Wu. (They requested not to use their real names for privacy concerns.) Their accounts showcase different facets of why Haigui employment in China is so dire. Until the job market in China improves and stops favoring nepotism, the number of Haigui will continue to rise as more and more Chinese students leave the country in search of better futures.Journalis

Design of a 3 GHz fine resolution LC DCO

In this thesis, the design of a fine resolution LC digitally controlled oscillator (DCO) is introduced. Two NMOS varactor banks are used to achieve 12 bits medium and fine frequency tuning. Both delta-sigma modulator and capacitive divider circuit are implemented to achieve a finer resolution and a larger dynamic range. The LC-oscillator has a coarse tuning range from 3.05 GHz to 3.85 GHz and a fine tuning range of 50MHz. It features a phase noise level of -115dBc/Hz at 1MHz frequency offset and consumes 5.4mW. Efficient simulation methodology is explored. Finally, this DCO is simulated in an All-Digital Phase Locked Loop (ADPLL) with other ideal behavior blocks implemented using Verilog-A, and the performance of the DCO is evaluated.Electrical and Computer Engineerin

Assessment of zonal isolation risk to changes in design parameters

The Well Containment Screening Tool (WCST) focuses on well integrity evaluation after well control incident. The WCST favors a greater wall thickness and, hence, a narrower cementing annulus, potentially increasing the risk of cement loss. We develop a structured and systematic physical model to simulate and track formation damage. A simulation process is conducted to assess the sensitivity of zonal isolation risk as design parameters are changed. In this paper, a physical model involving wellbore, casing and cement fluid is developed to understand the interaction between cement fluid and the formation. Two failure metrics are defined that provide a comprehensive understanding of the zonal isolation risk. Quantitative risk assessment is implemented with Monte Carlo simulation to assess the risk of zonal isolation problems when design parameters are changed. Models of production casing and intermediate casing are studied to verify the generality of this analysis. Taking both failure metrics into consideration, sensitivity analysis for models of production casing and intermediate casing present common observations regarding changes of design parameters. Our analysis suggests that minor increases (within 0.05”) in casing thickness, due to increased outer diameter, has little influence on the risk of cement loss, as does slight decreases in mean open hole diameter (within 0.05”). To verify the generality of this approach, in addition to casing and wellbore parameters, the sensitivity to cement fluid flow rate is analyzed. We find that risk is not significantly affected by small increase of flowrate (e.g. from 40 to 100 gpm). This paper applies a novel quantitative risk analysis to assess the influence of different design parameters on zonal isolation problems. This approach, if well implemented, can help to assess the impact of changes in design parameters (e.g., casing length and depth, mud density and cement fluid density, etc.) on drilling safety. It can also help to inform drilling decisions by providing forecasts of zonal isolation risk for particular geological condition.Mechanical Engineerin

Choosing the proper link function for binary data

textSince generalized linear model (GLM) with binary response variable is widely used in many disciplines, many efforts have been made to construct a fit model. However, little attention is paid to the link functions, which play a critical role in GLM model. In this article, we compared three link functions and evaluated different model selection methods based on these three link functions. Also, we provided some suggestions on how to choose the proper link function for binary data.Statistic

The tumor-promoting functions of Ataxia-telangiectasia mutated (ATM) in cancer cells

textAtaxia-telangiectasia mutated (ATM) protein kinase regulates the DNA damage response (DDR) and is associated with cancer suppression by protecting cells from DNA double-strand breaks (DSBs). However, how ATM functions outside of DSB signaling is less clearly understood. Here, we report a new cancer-promoting role for ATM in stimulating cell migration and invasion independently of DSB signaling or induction. We used two highly metastatic human breast cancer cell lines to corroborate that ATM is required for cell migration and invasion. Microarray analysis of cells depleted for ATM identified interleukin-8 (IL-8) as a target since the exogenous addition of IL-8 rescued migration and invasion defects in ATM-deficient cells. Finally, ATM depletion in human cancer cells reduced lung metastasis in a mouse xenograft model. These findings shed light on tumor-promoting functions of ATM. Therefore, in addition to its canonical roles in tumor suppression, ATM promotes tumor progression as well.Cellular and Molecular Biolog

World Heritage site management : protecting a site in its landscape, a Maltese case-study

A seminar presented at the Forum UNESCO University and Heritage on protecting the megalithic temple site of Mnajdra on Malta. The seminar was held due to a violent vandalistic attack on the temple site which shocked and angered the wider community. This incident served to highlight some potentially serious shortcomings in implementation of the World Heritage Convention (WHC) on a local level, with particular reference to its intention to protect sites and landscapes of 'outstanding universal value'. This paper examines the response of the Maltese community and WHS management team to the incident.peer-reviewe

Effect of fiber diameter and web porosity on breathability of nanofiber mats at various test conditions

textBarrier fabrics laminated with nanofiber membranes are used in protective textiles due to their ability to achieve high breathability or water vapor transmission rate (WVTR) while maintaining required barrier properties. The objective of this thesis is to investigate the factors impacting nanofiber membrane breathability. To achieve this objective, the effect of test conditions on breathability, and the relationship between fiber diameter, web porosity and breathability were explored. Nanofiber membranes were solution-spun by electrospinning from 15wt% and 20wt% PA6 solution concentrations, and by forcespinning from 20wt% and 25wt% concentrations. Three web area densities were made from each spinning method and solution combination: 5GSM, 10GSM and 15GSM. In order to investigate the impact of measurement conditions, breathability of all samples was measured by upright cup method (ASTM E96B) at two relative humidity levels (20% and 50%), and three air flow velocity levels (300fpm, 500fpm and 700fpm). The results showed that WVTR of all samples increased significantly when decreasing humidity or increasing air flow velocity. Webs with a lower density (5GSM or 10GSM) had higher changes of WVTR than those with a higher density (10GSM or 15GSM). These results indicate an interaction between the ambient conditions and the nanoweb structure, whereby conditions that are more conducive to water vapor transmission, such as 20%RH and 700fpm, are more discriminant between membranes. Both electropspun and forcespun membranes processed from the lower concentration solutions (15wt%, and 20wt%, respectively) exhibited smaller fiber diameters and smaller mean pore size. Overall, WVTR values varied with membrane thickness, and with solution concentration following a similar pattern as porosity. These effects were more accentuated for the forcespun samples, which had considerably larger pores (2811-5230nm) than the electrospun counterparts (163-298nm). Furthermore, samples forcespun by 20wt% solution were found to have clearly higher WVTR (1587-2194g/m²/24h at 700fpm) than electrospun samples (1526-1614g/m²/24h at 700fpm). This can be explained by the significant difference of pore size between electrospun and forcespun webs. It was concluded that breathability of forcespun samples, particularly those low density ones, could be effectively adjusted by solution concentration and is more sensitive to change of test conditions than that of electrospun webs.Textile and Apparel Technolog